The phenomenon of magneto resistance (MR) refers to the property of some materials that the electrical resistance, R, depends on the applied magnetic field, B. There is a growing family of MR phenomena. “Classical MR” which varies as B2 is too small for practical application. “Anisotropic MR” (AMR) is a property of ferromagnetic metals such as iron. Its magnitude is generally below 1%. “Colossal MR” (CMR) is exhibited by ferromagnetic oxides and occurs near the Curie-point. There are two severe problems of CMR with respect to application: first, it occurs only at unpractical large B and, second, at low temperatures. The current hard-disk drive technology uses the giant magneto resistance (GMR) effect which occurs in thin film multilayers of magnetic and normal metals. Large negative changes in resistance (≈10%) are seen in small fields, B≈10 mT. Concurrently, organic conjugated materials have also been developed and used to manufacture promising devices such as organic light emitting diodes (OLEDs), photovoltaic cells and field effect transistors.
Many of the currently known magneto resistive effects require measurements at very low temperatures and very high magnetic fields. These extreme temperature and magnetic field conditions have proven to be prohibitive to the development of economically and commercially useful applications of magneto resistive organic materials, data storage and retrieval and quantum information applications. As such, there is still a need in the art for the discovery and development of organic semi conductive materials and devices that can exhibit weak field magneto resistive properties at least substantially independent of specific temperature and thus enabling their use in a variety of current and future magneto resistance technologies.